Coccidioidomycosis or “Valley Fever” (VF) is caused by the fungus Coccidioides sp., which lives in soils of the southwestern US and San Juaquin Valley Calif. When soil is disturbed, humans and animals can inhale fungal spores that germinate in the lung to produce a respiratory infection that ranges in severity from mild to life threatening. An estimated 150,000 infections occur annually, and about 60% occur in Arizona. In Arizona in 2009 over 300,000 tests for Valley Fever were ordered by physicians. Coccidioidomycosis is a respiratory illness that is acquired through inhalation of airborne arthroconidia (spores), and produces a spectrum of illness, ranging from mild to severe and life-threatening pulmonary illness. Maricopa County has been the epicenter of a coccidioidal epidemic for years, with the incidence rising nearly six-fold since 1993.
Coccidioidomycosis in humans and dogs is difficult to diagnose and is often misdiagnosed as bacterial or viral community acquired pneumonia in humans. If a patient is suspected of having VF, serologic testing is performed, i.e. serum is tested for the presence of antibodies to coccidioidal antigens. Currently available tests to distinguish VF from other community acquired pneumoniae are based on the ability of patients to mount an antibody response to the fungus. Unfortunately, the antibody-based tests are inadequate for many patients because it may take weeks to months to develop such an antibody response (leading to delayed diagnosis), and many immunocompromised patients are unable to mount any antibody response at all. The problem is that even if a patient does not possess antibodies against the fungus, he/she may still have the disease. It may then become necessary to perform an invasive procedure such as bronchoalveolar lavage or biopsy of lung or other infected tissues to determine by culture or by direct histopathological exam if the fungus is present. Such procedures are expensive and put the patient at risk for procedure-related complications. Therefore a blood or other bodily fluid test to detect coccidioidal proteins would allow a more definitive diagnosis to be made even if a subject's serology is negative.